JP7559370B2 - Phenoxy resin composition and resin material - Google Patents

Description

The present invention relates to a phenoxy resin composition and a resin material.

So far, various developments have been made in heat dissipation and insulation materials. For example, the technology described in Patent Document 1 is known as this type of technology. Patent Document 1 describes a thermosetting resin composition that uses bisphenol A type epoxy resin, a phenolic hardener, and boron nitride particles as a thermally conductive filler as a heat dissipation and insulation material for electrical and electronic devices (Table 1 of Patent Document 1).

JP 2015-193504 A

However, as a result of the inventor's investigations, it was found that there is room for improvement in terms of fluidity and thermal conductivity in the bisphenol A type epoxy resin described in Patent Document 1 above.

After further investigation, the inventors found that there was room for improvement in the thermal conductivity of bisphenol A type epoxy resin, which is commonly used as a thermosetting resin in resin materials used for heat dissipation and insulation materials.

As a result of further investigation, it was found that thermal conductivity can be improved by using a phenoxy resin that has a mesogen structure in its molecule.
Further investigation revealed that the thermal conductivity of the phenoxy resin could be further improved by reducing the amount of low molecular weight components contained in the resin. However, excessive reduction in the amount of low molecular weight components could reduce the fluidity of the phenoxy resin, making it difficult to apply the resin to resin materials.

Based on this knowledge, further intensive research led to the discovery that the thermal conductivity and fluidity of the phenoxy resin can be improved by controlling the peak area of low molecular weight components with Mw of 1,000 or less within a specified range in the molecular weight distribution of the phenoxy resin composition obtained by GPC, and thus the present invention was completed.

According to the present invention,
A phenoxy resin having a mesogen structure in its molecule;
A low molecular weight component having a weight average molecular weight Mw of 1,000 or less;
A phenoxy resin composition comprising:
In the molecular weight distribution of the phenoxy resin composition obtained by gel permeation chromatography, the peak area of the low molecular weight component is 7.0% or more and 50.0% or less with respect to 100% of the total peak area.
A phenoxy resin composition is provided.

The present invention also provides a resin material containing the above-mentioned phenoxy resin composition.

The present invention provides a phenoxy resin composition with excellent fluidity and thermal conductivity, and a resin material using the same.

1 is a cross-sectional view showing a configuration of a metal base substrate according to an embodiment of the present invention.

The following describes an embodiment of the present invention with reference to the drawings. Note that in all drawings, similar components are given similar reference numerals and descriptions are omitted where appropriate. Also, the drawings are schematic and do not correspond to the actual dimensional ratios.

The phenoxy resin composition of the present embodiment will be outlined below.
The phenoxy resin composition contains a phenoxy resin having a mesogen structure in the molecule, and a low-molecular-weight component having a weight-average molecular weight Mw of 1,000 or less.
The phenoxy resin composition has a characteristic that, in the molecular weight distribution of the phenoxy resin composition obtained by gel permeation chromatography, the peak area of a low molecular weight component having a Mw of 1,000 or less is 7.0% or more and 50.0% or less with respect to 100% of the total peak area.

According to the findings of the present inventors, it has been found that the thermal conductivity can be improved by using a phenoxy resin having a mesogenic structure in the molecule, and further, the thermal conductivity can be further increased by reducing the low molecular weight components contained in the phenoxy resin.
However, it was found that excessive reduction in the content of low molecular weight components reduces the fluidity of the phenoxy resin, which can lead to an increase in melt viscosity and make it difficult to apply the resin to resin materials.

Further intensive research based on this knowledge revealed that by using the peak area of low molecular weight components with Mw of 1,000 or less as an index in the molecular weight distribution of the phenoxy resin composition obtained by GPC, the content of low molecular weight components can be appropriately controlled and the thermal conductivity and fluidity of the phenoxy resin can be improved. As a result of further investigation, it was found that fluidity can be improved by setting the peak area of the low molecular weight components to above the above lower limit, and that thermal conductivity can be improved by setting it to below the above upper limit.

The phenoxy resin composition of the present embodiment can be applied to resin materials together with other components depending on the purpose.
According to this embodiment, it is possible to provide a thermosetting resin composition (thermally conductive resin composition) containing the above-mentioned phenoxy resin composition, and, if necessary, a thermosetting resin, a curing agent, a curing accelerator, and other additives.

The thermosetting resin composition can be used in various forms, for example, in the form of a sheet or a substrate.
The thermosetting resin composition is not particularly limited, and can be used for a variety of purposes such as a heat dissipation material, an insulating material, and a semiconductor encapsulation material.

This thermosetting resin composition may contain various functional additives such as thermally conductive fillers, if necessary. Such a thermosetting resin composition can be used as a heat dissipation insulating material for electric and electronic devices. This heat dissipation insulating material may be used, for example, as a substrate material for mounting electronic components.

Electrical and electronic devices can use, for example, normal LED lighting devices (lighting devices equipped with LEDs as electronic components) and power supply devices (electronic devices equipped with power modules as electronic components). LEDs and power modules generate more heat than normal electronic components, so they operate in high-temperature environments and require a metal-based substrate. This thermosetting resin composition can provide a heat dissipation and insulation material that can be used for metal-based substrates.

The phenoxy resin composition of this embodiment is described in detail below.

The phenoxy resin composition contains a phenoxy resin having a mesogenic structure in the molecule.

The phenoxy resin composition contains a high molecular weight component (A) having a Mw of more than 1k and a low molecular weight component (B+C) having a Mw of 1k or less.
The low molecular weight component may contain two or more types of monomer component (C) contained in the above-mentioned phenoxy resin, and a low molecular weight component (B) having Mw of 1k or less and not including monomer component (C). The monomer components may include epoxy monomers and phenol monomers. The low molecular weight component (B) may be composed of one or more polymers of monomer component (C).

When the phenoxy resin is obtained by the reaction of a polyfunctional phenolic compound with a polyfunctional epoxy compound as described below, the low molecular weight component includes unreacted monomer components (polyfunctional phenolic compounds and polyfunctional epoxy compounds) (C) and low molecular weight components of the reaction product (low molecular weight components (B)). Low molecular weight components refer to those reactants excluding unreacted monomer components that have a weight average molecular weight of 1000 or less.

In this specification, the phenoxy resin composition may be defined as containing the high molecular weight component and the low molecular weight component, but not containing a solvent. However, the phenoxy resin composition may contain impurity components other than the high molecular weight component and the low molecular weight component, as long as the effect of the present invention is not impaired.

An example of the mesogenic structure-containing phenoxy resin is one that contains a structural unit derived from a phenol compound and a structural unit derived from an epoxy compound in the molecule, and at least one of these structural units contains a compound having a mesogenic structure.
Other examples of the mesogenic structure-containing phenoxy resin include those that contain, in the molecule, a structural unit derived from a mesogenic structure-containing phenol compound.

An example of the mesogen structure-containing phenoxy resin can be produced by a known method, for example, by reacting a polyfunctional phenol compound having two or more hydroxy groups in the molecule with a polyfunctional epoxy compound having two or more epoxy groups in the molecule.
That is, the phenoxy resin may contain a reaction compound of a polyfunctional phenol compound and a polyfunctional epoxy compound, either or both of which have a mesogen structure.

Other examples of the mesogenic structure-containing phenoxy resins can be produced by known methods, for example, by subjecting a mesogenic structure-containing phenolic compound having two or more phenol groups in the molecule to an addition polymerization reaction in epichlorohydrin.
That is, the phenoxy resin may contain an addition polymer of a phenol compound having a mesogen structure.

The above-mentioned phenoxy resin can be produced without a solvent or in the presence of a reaction solvent. The reaction solvent used can be an aprotic organic solvent, such as methyl ethyl ketone, dioxane, tetrahydrofuran, acetophenone, N-methylpyrrolidone, dimethyl sulfoxide, N,N-dimethylacetamide, N,N-dimethylformamide, sulfolane, or cyclohexanone. After completion of the reaction, the resin can be obtained as a solution in a suitable solvent by performing solvent replacement or the like. The phenoxy resin obtained by the solvent reaction can also be made into a solvent-free solid resin by performing a solvent removal process using an evaporator or the like.

Reaction catalysts that can be used in the production of the above-mentioned phenoxy resin include conventionally known polymerization catalysts such as alkali metal hydroxides, tertiary amine compounds, quaternary ammonium compounds, tertiary phosphine compounds, quaternary phosphonium compounds, and imidazole compounds.

The weight average molecular weight (Mw) of the phenoxy resin is usually 500 to 200,000. It is preferably 1,000 to 100,000, and more preferably 2,000 to 50,000. Mw is measured by gel permeation chromatography and is converted using a standard polystyrene calibration curve.

In this embodiment, the mesogenic structure has, for example, a structure represented by the following general formula (1) or (2).
-A ¹ -x-A ² -...(1)
-x-A ¹ -x-...(2)

In the above general formula (1) and general formula (2), A ¹ and A ² each independently represent an aromatic group, a condensed aromatic group, an alicyclic group, or an alicyclic heterocyclic group, and x each independently represent a direct bond or a divalent bonding group selected from the group consisting of -O-, -C=C-, -C≡C-, -CO-, -CO-O-, -CO-NH-, -CH=N-, -CH=N-N=CH-, -N=N-, and -N(O)=N-.

Here, A ¹ and A ² are preferably each independently selected from a hydrocarbon group having 6 to 12 carbon atoms and a benzene ring, a hydrocarbon group having 10 to 20 carbon atoms and a naphthalene ring, a hydrocarbon group having 12 to 24 carbon atoms and a biphenyl structure, a hydrocarbon group having 12 to 36 carbon atoms and having three or more benzene rings, a hydrocarbon group having 12 to 36 carbon atoms and having a condensed aromatic group, and an alicyclic heterocyclic group having 4 to 36 carbon atoms. ^{A 1} and A ² may be unsubstituted or may be a derivative having a substituent.

Specific examples of A ¹ and A ² in the mesogenic structure include phenylene, biphenylene, naphthylene, anthracenylene, cyclohexyl, pyridyl, pyrimidyl, thiophenylene, etc. These may be unsubstituted or may be derivatives having a substituent such as an aliphatic hydrocarbon group, a halogen group, a cyano group, or a nitro group.

As x corresponding to a bonding group (linking group) in the mesogenic structure, for example, a direct bond or a divalent substituent selected from the group consisting of -C=C-, -C≡C-, -CO-O-, -CO-NH-, -CH=N-, -CH=N-N=CH-, -N=N- or -N(O)=N- is preferred.
Here, the direct bond means a single bond, or a ring structure formed by bonding A ¹ and A ² in the mesogenic structure to each other. For example, the structure represented by the above general formula (1) may contain a naphthalene structure.

As the polyfunctional phenol compound, for example, a mesogen structure-containing compound represented by the following general formula (A) can be used. These may be used alone or in combination of two or more kinds.

In the above general formula (A), ^R1 and ^R3 each independently represent a hydroxy group, ^R2 and ^R4 each independently represent one selected from a hydrogen atom, a linear or cyclic alkyl group having 1 to 6 carbon atoms, a phenyl group, and a halogen atom, a and c each represent an integer of 1 to 3, and b and d each represent an integer of 0 to 2. However, a+b and c+d each represent an integer of 1 to 3. a+c may be 3 or more. n is 0 or 1.

As the polyfunctional epoxy compound, for example, a mesogen structure-containing compound represented by the following general formula (B) can be used. These may be used alone or in combination of two or more types.

In the above general formula (B), ^R5 and ^R7 each independently represent a glycidyl ether group, ^R6 and ^R8 each independently represent one selected from a hydrogen atom, a linear or cyclic alkyl group having 1 to 6 carbon atoms, a phenyl group, and a halogen atom, e and g each independently represent an integer of 1 to 3, and f and h each independently represent an integer of 0 to 2, provided that e+f and g+h each independently represent an integer of 1 to 3, and n is 0 or 1.

Furthermore, R in the above general formula (A) and general formula (B) represents the above-mentioned -A ¹ -x-A ² -, -x-A ¹ -x-, or -x-, respectively. Note that, in the above general formula (A) and general formula (B), when n is 0, a condensed ring may be formed by two benzene rings.

Specific examples of ^R2 , ^R4 , ^R6 and ^R8 include a hydrogen atom, a methyl group, an ethyl group, a propyl group, a butyl group, a chlorine atom, a bromine atom and the like, with a hydrogen atom or a methyl group being particularly preferred.

As the polyfunctional epoxy compound containing the mesogenic structure, for example, an addition polymer of the compound represented by the general formula (B) above may be used. These may be used alone or in combination of two or more kinds.

The phenoxy resin of this embodiment contains a multi-branched structure in which the ring structure "Ph-(R) _n -Ph" derived from these compounds is linked via the following group (a) formed by bonding a hydroxyl group of the above-mentioned polyfunctional phenol compound with a glycidyl ether group of the above-mentioned polyfunctional epoxy compound. In the following group (a), * indicates a bond.

Among the above-mentioned polyfunctional phenol compounds and polyfunctional epoxy compounds, polyfunctional phenol compounds having three or more hydroxy groups in the molecule, and polyfunctional epoxy compounds having two or more epoxy groups in the molecule may be used.
That is, the phenoxy resin may contain a branched reaction compound between a polyfunctional phenol compound having three or more hydroxy groups in the molecule and a polyfunctional epoxy compound having two or more epoxy groups in the molecule.

The polyfunctional phenol compound having three or more hydroxy groups in the molecule can include, for example, polyphenols or polyphenol derivatives.
The polyphenol is a compound containing three or more phenolic hydroxyl groups in the molecule. In addition, the polyphenol is preferably one having the above-mentioned mesogen structure in the molecule. For example, the mesogen structure may be a biphenyl skeleton, a phenylbenzoate skeleton, an azobenzene skeleton, an amide skeleton, a stilbene skeleton, or the like.
The polyphenol derivative includes a compound in which a substitutable position of a polyphenol compound having three or more phenolic hydroxy groups and a mesogenic structure is changed to another substituent.

In this embodiment, the branched reaction compound can be obtained using one or more of the above-mentioned polyfunctional phenolic compounds, including a polyfunctional phenolic compound having at least three or more hydroxyl groups in the molecule, and one or more of the above-mentioned polyfunctional epoxy resins.

For example, a combination of a trifunctional phenol compound and a difunctional epoxy compound, or a combination of a trifunctional phenol compound, a difunctional phenol compound and a difunctional epoxy compound may be used.
As the trifunctional phenol compound, for example, resveratrol represented by the following chemical formula can be used.

As the bifunctional phenol compound, for example, a compound in which the hydroxy groups of ^R1 and ^R3 in the above general formula (A) are bonded to the para-position of each benzene ring can be used.
Furthermore, as the bifunctional epoxy compound, there can be used one in which the glycidyl ether groups of ^R5 and ^R7 in the above general formula (B) are bonded to the para-position of each benzene ring.

In addition, when the polyfunctional phenol compound represented by the general formula (A) is a bifunctional phenol compound having a naphthalene ring as a condensed ring, the two hydroxyl groups of ^R1 and/or ^R3 can be bonded to any of the 1st and 3rd positions, the 1st and 4th positions, the 1st and 5th positions, the 1st and 6th positions, the 2nd and 3rd positions, the 2nd and 6th positions, the 2nd and 7th positions, or the 2nd and 8th positions of the naphthalene ring. From the viewpoint of thermal conductivity characteristics and heat resistance, it is more preferable to use a bifunctional phenol compound in which the substitution positions of the hydroxyl groups are the 1st and 4th positions, the 1st and 5th positions, the 1st and 6th positions, the 2nd and 3rd positions, the 2nd and 6th positions, or the 2nd and 7th positions of the naphthalene ring.

In addition, when the polyfunctional epoxy compound represented by the general formula (B) is a bifunctional epoxy compound having a naphthalene ring as a condensed ring, the two glycidyl ether groups of ^R5 and/or ^R7 can be bonded to any of the 1st and 3rd positions, the 1st and 4th positions, the 1st and 5th positions, the 1st and 6th positions, the 2nd and 3rd positions, the 2nd and 6th positions, the 2nd and 7th positions, or the 2nd and 8th positions of the naphthalene ring. From the viewpoint of thermal conductivity characteristics and heat resistance, it is more preferable to use a bifunctional epoxy compound in which the substitution positions of the glycidyl ether groups are the 1st and 4th positions, the 1st and 5th positions, the 1st and 6th positions, the 2nd and 3rd positions, the 2nd and 6th positions, or the 2nd and 7th positions of the naphthalene ring.

The above-mentioned branched reactive compound (branched phenoxy resin) can be obtained by combining a trifunctional phenolic compound and a bifunctional epoxy compound, or by combining a trifunctional phenolic compound, a bifunctional phenolic compound, and a bifunctional epoxy compound.

For example, a branched reaction compound (branched phenoxy resin) obtained by combining a trifunctional phenolic compound and a difunctional epoxy compound contains a repeating unit represented by the following general formula (b):

In formula (b), b, d, R, n, ^R2 and ^R4 are defined as in formula (A), and f, h, ^R6 and ^R8 are defined as in formula (B). * represents a bond.
In the present embodiment, the branched reactive compound (branched phenoxy resin) may contain structural units containing unreacted hydroxyl groups and/or unreacted glycidyl ether groups in addition to the above structural units in which all of the hydroxyl groups and glycidyl ether groups have reacted.

Among the polyfunctional phenol compounds and polyfunctional epoxy compounds, bifunctional phenol compounds and bifunctional epoxy compounds may be used alone or in combination of two or more.
That is, the phenoxy resin may contain a linear reaction compound of a bifunctional phenol compound having two hydroxyl groups in the molecule and a bifunctional epoxy compound having two epoxy groups in the molecule.

The bifunctional phenol compound may be one in which the hydroxyl groups ^R1 and ^R3 in the general formula (A) are bonded to the para-position of the respective benzene rings, and the bifunctional epoxy compound may be one in which the glycidyl ether groups ^R5 and ^R7 in the general formula (B) are bonded to the para-position of the respective benzene rings.

In addition, when the polyfunctional phenol compound represented by the general formula (A) is a bifunctional phenol compound having a naphthalene ring as a condensed ring, the two hydroxyl groups of ^R1 and/or ^R3 may be bonded to any one of the 1st and 3rd positions, the 1st and 4th positions, the 1st and 5th positions, the 1st and 6th positions, the 2nd and 3rd positions, the 2nd and 6th positions, the 2nd and 7th positions, or the 2nd and 8th positions of the naphthalene ring. From the viewpoint of thermal conductivity characteristics and heat resistance, it is more preferable to use a bifunctional phenol compound in which the substitution positions of the hydroxyl groups are selected from the 1st and 4th positions, the 1st and 5th positions, the 1st and 6th positions, the 2nd and 3rd positions, the 2nd and 6th positions, or the 2nd and 7th positions of the naphthalene ring.

In addition, when the polyfunctional epoxy compound represented by the general formula (B) is a bifunctional epoxy compound having a naphthalene ring as a condensed ring, the two glycidyl ether groups of ^R5 and/or ^R7 can be bonded to any one of the 1st and 3rd positions, the 1st and 4th positions, the 1st and 5th positions, the 1st and 6th positions, the 2nd and 3rd positions, the 2nd and 6th positions, the 2nd and 7th positions, or the 2nd and 8th positions of the naphthalene ring. From the viewpoint of thermal conductivity characteristics and heat resistance, it is more preferable to use a bifunctional epoxy compound in which the substitution positions of the glycidyl ether groups are selected from the 1st and 4th positions, the 1st and 5th positions, the 1st and 6th positions, the 2nd and 3rd positions, the 2nd and 6th positions, or the 2nd and 7th positions of the naphthalene ring.

By using such a bifunctional phenol compound and a bifunctional epoxy compound in combination, the above-mentioned linear reaction compound (linear phenoxy resin) can be obtained.

For example, a linear reaction compound (linear phenoxy resin) obtained by combining a bifunctional phenol compound and a bifunctional epoxy compound contains a structural unit (repeating unit) represented by the following general formula (c). In the following groups, * indicates a bond.

In formula (c), b, d, R, n, ^R2 and ^R4 are defined as in formula (A), and f, h, ^R6 and ^R8 are defined as in formula (B). * represents a bond.
In the present embodiment, the linear reaction compound (linear phenoxy resin) may contain structural units containing unreacted hydroxyl groups and/or unreacted glycidyl ether groups in addition to the above structural units in which all of the hydroxyl groups and glycidyl ether groups have reacted.

The branched phenoxy resin and the linear phenoxy resin may have an epoxy group or a hydroxy group at the molecular terminal and an epoxy group or a hydroxy group inside the molecule. By having an epoxy group at the terminal or inside, a crosslinking reaction can be formed, and therefore the heat resistance can be improved.
Furthermore, by having a rigid, electron-conjugated, straight-chain structural unit, the heat dissipation characteristics can be improved.

In this embodiment, a molecular weight distribution curve for the phenoxy resin composition is obtained using GPC (gel permeation chromatography).
The weight average molecular weight (Mw), number average molecular weight (Mn), and dispersity (PDI: Mw/Mn) of the phenoxy resin are calculated using polystyrene-equivalent values obtained from a calibration curve of standard polystyrene (PS) obtained by GPC measurement.
The measurement conditions for GPC are, for example, as follows.
Gel permeation chromatography device HLC-8320GPC manufactured by Tosoh Corporation
Column: TSK-GEL GMH, G2000H, Super HM-M manufactured by Tosoh Corporation
Detector: RI detector for liquid chromatography Measurement temperature: 40°C
Solvent: THF
Sample concentration: 2.0 mg/ml

The weight average molecular weight (Mw), number average molecular weight (Mn), and polydispersity (PDI: Mw/Mn) of the high molecular weight component (A) with Mw of more than 1k are calculated using polystyrene equivalent values obtained from the calibration curve of standard polystyrene (PS) obtained by GPC measurement.

In the above phenoxy resin composition, the weight average molecular weight (Mw) of the high molecular weight component (A) having an Mw of more than 1k is, for example, more than 1,000 and not more than 200,000, preferably 1,500 to 100,000, and more preferably 2,000 to 50,000. By setting the above Mw to the lower limit or more, the thermal conductivity of the phenoxy resin can be improved. On the other hand, by setting the above Mw to the upper limit or less, the fluidity of the phenoxy resin can be improved.

In the above phenoxy resin composition, the dispersity (Mw/Mn) of the high molecular weight component (A) having an Mw of more than 1k is, for example, 1.00 to 5.00, preferably 1.20 to 4.00, and more preferably 1.30 to 3.50. By setting the dispersity to the lower limit or higher, the thermal conductivity of the phenoxy resin can be improved. On the other hand, by setting the dispersity to the upper limit or lower, the fluidity of the phenoxy resin can be improved.

In this specification, "~" indicates that the upper and lower limits are included unless otherwise specified.

The peak area corresponding to the low molecular weight components (B+C) having Mw of 1k or less in the above-mentioned phenoxy resin composition is calculated from the ratio of the total area of components having a weight average molecular weight Mw of 1000 or less to the total area (100%) of the entire molecular weight distribution based on data on molecular weight obtained, for example, by GPC measurement.
The low molecular weight component (B+C) having a Mw of 1k or less includes a monomer component (C) and a low molecular weight component (B) having a Mw of 1,000 or less that does not contain a monomer component (C).
The total peak area of 100% refers to the sum of the peak areas of the high molecular weight component (A) having a Mw of more than 1 k, the monomer component (C), and the low molecular weight component (B) having a Mw of 1,000 or less and not including the monomer component (C).

The lower limit of the peak area of the low molecular weight components (B+C) is, for example, 7.0% or more, preferably 10.0% or more, and more preferably 11.0% or more, relative to 100% of the total peak area. This improves the fluidity of the phenoxy resin. On the other hand, the upper limit of the peak area of the low molecular weight components (B+C) is, for example, 50.0% or less, preferably 48.0% or less, and more preferably 45.0% or less, relative to 100% of the total peak area. This improves the thermal conductivity of the phenoxy resin.

In addition, in the molecular weight distribution of the phenoxy resin composition obtained by GPC measurement, the lower limit of the peak area (%) of the low molecular weight component (B) having an Mw of 1,000 or less relative to 100% of the total peak area is, for example, 2.0% or more, preferably 2.3% or more, and more preferably 2.5% or more. This can improve the fluidity of the phenoxy resin. The upper limit of the peak area (%) of the low molecular weight component (B) having an Mw of 1,000 or less relative to 100% of the total peak area is, for example, 25.0% or less, preferably 24.0% or less, and more preferably 23.0% or less. This can improve the thermal conductivity of the phenoxy resin.

The low molecular weight component (B) with Mw of 1,000 or less is defined as not containing monomer component (C). The peak area ratio of this low molecular weight component (B) with Mw of 1,000 or less represents the content ratio of low-molecular weight components (low molecular weight polymer components) contained in the low molecular weight component.

In addition, in the molecular weight distribution of the phenoxy resin composition obtained by GPC measurement, the lower limit of the peak area (%) of the monomer component (C) relative to 100% of the total peak area is, for example, 1.0% or more, preferably 2.0% or more, and more preferably 3.0% or more. This can improve the fluidity of the phenoxy resin. The upper limit of the peak area (%) of the monomer component (C) relative to 100% of the total peak area is, for example, 25.0% or less, preferably 23.0% or less, and more preferably 22.0% or less. This can improve the thermal conductivity of the phenoxy resin.

In this embodiment, for example, by appropriately selecting the type and amount of each component contained in the phenoxy resin composition, the preparation method of the phenoxy resin, etc., it is possible to control the peak area of the low molecular weight component (B + C), the peak area of the low molecular weight component (B), and the Mw and Mw/Mn of the high molecular weight component (A) in the phenoxy resin composition. Among these, for example, appropriately selecting the synthesis conditions of the phenoxy resin, such as the reaction temperature, reaction time, and removal of monomers, is an element for setting the peak area of the low molecular weight component (B + C), the peak area of the low molecular weight component (B), and the Mw and Mw/Mn of the high molecular weight component (A) in the phenoxy resin composition to the desired numerical range.

The following describes a resin material using the phenoxy resin composition of this embodiment.

The resin material contains the phenoxy resin composition. The content can be appropriately adjusted based on various applications and other compounding components. For example, the content of the phenoxy resin composition in the thermosetting resin composition used for the heat dissipation insulating material is, for example, 1% by mass to 70% by mass, preferably 2% by mass to 50% by mass, and more preferably 3% by mass to 45% by mass, based on the non-volatile components (100% by mass) of the thermosetting resin composition not including the filler.

Here, the term "filler" includes ordinary fillers such as a thermally conductive filler, an inorganic filler, or an organic filler, which will be described later. That is, a thermosetting resin composition that does not contain a filler is composed of resin components other than a filler, and includes, as the resin components, for example, a thermosetting resin and a phenoxy resin.
It also refers to the non-volatile content (100 mass%) in the thermosetting resin composition, and refers to the remainder excluding water, solvents, and other solvents.

The thermosetting resin composition may contain a thermosetting resin other than the phenoxy resin.
Examples of the thermosetting resin include epoxy resin, polyimide resin, benzoxazine resin, unsaturated polyester resin, phenol resin, melamine resin, silicone resin, cyanate resin, bismaleimide resin, acrylic resin, phenol derivatives, and derivatives thereof. As the thermosetting resin, a monomer, oligomer, or polymer having two or more reactive functional groups in one molecule can be used, and the molecular weight or molecular structure is not particularly limited. These may be used alone or in combination of two or more.

The thermosetting resin composition may contain a curing agent, if necessary.
The curing agent is selected according to the type of thermosetting resin, and is not particularly limited as long as it reacts with the thermosetting resin.
Examples of the curing agent include phenolic resin curing agents, amine curing agents, acid anhydride curing agents, mercaptan curing agents, etc. These may be used alone or in combination of two or more kinds.

(Cure Accelerator)
The thermosetting resin composition may contain a curing accelerator as necessary.
The type and amount of the curing accelerator are not particularly limited, but an appropriate one can be selected from the viewpoints of reaction rate, reaction temperature, storage property, and the like.

Examples of the curing accelerator include imidazoles, organic phosphorus compounds, tertiary amines, phenolic compounds, organic acids, and the like. These may be used alone or in combination of two or more. Among these, from the viewpoint of improving heat resistance, it is preferable to use nitrogen atom-containing compounds such as imidazoles.

The thermosetting resin composition may contain a thermally conductive filler.
The thermally conductive filler may contain, for example, highly thermally conductive inorganic particles having a thermal conductivity of 20 W/m·K or more. The highly thermally conductive inorganic particles may contain, for example, at least one selected from alumina, aluminum nitride, boron nitride, silicon nitride, silicon carbide, and magnesium oxide. These may be used alone or in combination of two or more.

The thermally conductive filler may contain boron nitride in the form of monodisperse particles, agglomerated particles, or a mixture thereof, of scaly boron nitride. The scaly boron nitride may be granulated. By using agglomerated particles of scaly boron nitride, the thermal conductivity can be further increased. The agglomerated particles may be sintered particles or non-sintered particles.

The thermosetting resin composition may contain a silane coupling agent.
This can improve the compatibility of the thermally conductive filler in the thermosetting resin composition. The coupling agent may be added to the thermosetting resin composition, or may be used by treating the surface of the thermally conductive filler.

The thermosetting resin composition of this embodiment may contain other components in addition to the components described above. Examples of such other components include an antioxidant and a leveling agent.

The thermosetting resin composition of the present embodiment can be produced, for example, by the following method.
The above components can be dissolved in a solvent, mixed, and stirred to prepare a resin varnish (a thermosetting resin composition in the form of a varnish). For this mixing, various mixers such as an ultrasonic dispersion type, a high-pressure collision type dispersion type, a high-speed rotation dispersion type, a bead mill type, a high-speed shear dispersion type, and a rotation-revolution type dispersion type can be used.

The above solvents are not particularly limited, but include acetone, methyl isobutyl ketone, toluene, ethyl acetate, cyclohexane, heptane, cyclohexanone, tetrahydrofuran, dimethylformamide, dimethylacetamide, dimethylsulfoxide, ethylene glycol, cellosolve-based solvents, carbitol-based solvents, anisole, and N-methylpyrrolidone.

(Resin sheet)
The resin sheet of the present embodiment includes a carrier substrate and a resin layer formed on the carrier substrate and made of the thermosetting resin composition of the present embodiment.

The resin sheet can be obtained, for example, by applying a varnish-like thermosetting resin composition onto a carrier substrate to obtain a coating film (resin layer) and then carrying out a solvent removal process. The solvent content in the resin sheet can be 10% by weight or less based on the entire thermosetting resin composition. For example, the solvent removal process can be carried out under conditions of 80°C to 200°C and 1 minute to 30 minutes.

In this embodiment, the carrier substrate may be, for example, a polymer film or a metal foil. Examples of the polymer film include, but are not limited to, polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polycarbonates, release papers such as silicone sheets, and heat-resistant thermoplastic resin sheets such as fluorine-based resins and polyimide resins. Examples of the metal foil include, but are not limited to, copper and/or copper-based alloys, aluminum and/or aluminum-based alloys, iron and/or iron-based alloys, silver and/or silver-based alloys, gold and gold-based alloys, zinc and zinc-based alloys, nickel and nickel-based alloys, and tin and tin-based alloys.

(Resin substrate)
The resin substrate of the present embodiment includes an insulating layer made of the cured product of the thermosetting resin composition. This resin substrate can be used as a material for a printed circuit board on which electronic components such as LEDs and power modules are mounted.

(Metal base substrate)
As an example of this embodiment, a metal base substrate 100 will be described with reference to FIG.
FIG. 1 is a cross-sectional view showing an example of the configuration of a metal base substrate 100. As shown in FIG.
As shown in Fig. 1, the metal base substrate 100 may include a metal substrate 101, an insulating layer 102 provided on the metal substrate 101, and a metal layer 103 provided on the insulating layer 102. The insulating layer 102 may be made of one selected from the group consisting of a resin layer made of the above-mentioned thermosetting resin composition, a cured product of the thermosetting resin composition, and a laminate. Each of these resin layers and laminates may be made of a thermosetting resin composition in a B-stage state before the circuit processing of the metal layer 103, and may be a cured product obtained by curing the resin composition after the circuit processing.

The metal layer 103 is provided on the insulating layer 102 and is processed into a circuit. Examples of metals constituting the metal layer 103 include one or more selected from copper, copper alloys, aluminum, aluminum alloys, nickel, iron, tin, and the like. Among these, the metal layer 103 is preferably a copper layer or an aluminum layer, and is particularly preferably a copper layer. By using copper or aluminum, the circuit processability of the metal layer 103 can be improved. The metal layer 103 may be a metal foil available in a plate form, or a metal foil available in a roll form.

The lower limit of the thickness of the metal layer 103 is, for example, 0.01 mm or more, and preferably 0.035 mm or more, so that the metal layer 103 can be applied to applications requiring a high current.
The upper limit of the thickness of the metal layer 103 is, for example, 10.0 mm or less, and preferably 5 mm or less. If the thickness is less than this value, the circuit processability can be improved, and the substrate as a whole can be made thinner.

The metal substrate 101 has the role of dissipating heat accumulated in the metal base substrate 100. The metal substrate 101 is not particularly limited as long as it is a heat-dissipating metal substrate, but may be, for example, a copper substrate, a copper alloy substrate, an aluminum substrate, or an aluminum alloy substrate, with a copper substrate or an aluminum substrate being preferred, and a copper substrate being more preferred. By using a copper substrate or an aluminum substrate, the heat dissipation properties of the metal substrate 101 can be improved.

The thickness of the metal substrate 101 can be appropriately set as long as the object of the present invention is not impaired.
The upper limit of the thickness of the metal substrate 101 is, for example, 20.0 mm or less, and preferably 5.0 mm or less. By using a metal substrate 101 having a thickness of this value or less, the workability of the metal base substrate 100 in the outer shaping, cutting, and the like can be improved.
The lower limit of the thickness of the metal substrate 101 is, for example, 0.01 mm or more, and preferably 0.6 mm or more. By using a metal substrate 101 having a thickness of this value or more, the heat dissipation properties of the metal base substrate 100 as a whole can be improved.

In this embodiment, the metal base substrate 100 can be used for various substrate applications, but because of its excellent thermal conductivity and heat resistance, it can be used as a printed circuit board that uses LEDs and power modules.
The metal base substrate 100 can have a metal layer 103 that is circuitized by etching or the like into a pattern. In this metal base substrate 100, a solder resist (not shown) may be formed on the outermost layer, and connection electrodes may be exposed so that electronic components can be mounted thereon by exposure and development.

（一般式（Ａ）中、Ｒ ^１ およびＲ ^３ は、それぞれ独立に、ヒドロキシ基を表し、Ｒ ^２ およびＲ ^４ は、それぞれ独立に、水素原子、炭素数１～６の鎖状もしくは環状アルキル基、フェニル基およびハロゲン原子から選択される１種を表し、ａおよびｃはそれぞれ１～３の整数であり、ｂおよびｄはそれぞれ０～２の整数である。ただし、ａ＋ｂおよびｃ＋ｄは、それぞれ１～３のいずれかである。Ｒは、前記一般式（１）で表されるメソゲン構造を表す。ｎは０または１である。ｎが０の場合、２つのベンゼン環により縮合環を形成してもよい。）

（一般式（Ｂ）中、Ｒ ^５ およびＲ ^７ は、それぞれ独立に、グリシジルエーテル基を表し、Ｒ ^６ およびＲ ^８ は、それぞれ独立に、水素原子、炭素数１～６の鎖状もしくは環状アルキル基、フェニル基およびハロゲン原子から選択される１種を表し、ｅおよびｇはそれぞれ１～３の整数であり、ｆおよびｈはそれぞれ０～２の整数である。ただし、ｅ＋ｆおよびｇ＋ｈは、それぞれ１～３のいずれかである。Ｒは、前記一般式（１）で表されるメソゲン構造を表す。ｎは０または１である。ｎが０の場合、２つのベンゼン環により縮合環を形成してもよい。）
［５］
［４］に記載のフェノキシ樹脂組成物であって、
前記分子内にメソゲン構造を有するフェノキシ樹脂が、下記一般式（ｂ）で表される繰り返し単位を含む、フェノキシ樹脂組成物。

（一般式（ｂ）中、ｂ、ｄ、Ｒ、ｎ、Ｒ ^２ およびＲ ^４ は一般式（Ａ）と同義であり、ｆ、ｈ、Ｒ ^６ およびＲ ^８ は一般式（Ｂ）と同義である。＊は結合手を表す。）
［６］
［４］に記載のフェノキシ樹脂組成物であって、
前記分子内にメソゲン構造を有するフェノキシ樹脂が、下記一般式（ｃ）で表される繰り返し単位を含む、フェノキシ樹脂組成物。

（一般式（ｃ）中、ｂ、ｄ、Ｒ、ｎ、Ｒ ^２ およびＲ ^４ は一般式（Ａ）と同義であり、ｆ、ｈ、Ｒ ^６ およびＲ ^８ は一般式（Ｂ）と同義である。＊は結合手を表す。）
［７］
［３］～［６］のいずれかに記載のフェノキシ樹脂組成物であって、
前記フェノキシ樹脂は、前記多官能フェノール化合物と前記多官能エポキシ化合物との反応により得られ、
前記低分子量成分は、未反応モノマーおよび当該未反応モノマーの低核体を含む、フェノキシ樹脂組成物。
［８］
［３］～［７］のいずれか一つに記載のフェノキシ樹脂組成物であって、
当該フェノキシ樹脂組成物の分子量分布において、全ピーク面積１００％に対する、モノマー成分を含まない前記低分子量成分のピーク面積が、２．０％以上２５．０％以下を満たす、
フェノキシ樹脂組成物。
［９］
［１］～［８］のいずれか一つに記載のフェノキシ樹脂組成物であって、
Ｍｗが１，０００超えの高分子量成分のＭｗが１，０００を超え２００，０００以下である、フェノキシ樹脂組成物。
［１０］
［１］～［９］のいずれか一つに記載のフェノキシ樹脂組成物であって、
Ｍｗが１，０００超えの高分子量成分の分子量分布（Ｍｗ／Ｍｎ）が１．００以上５．００以下である、フェノキシ樹脂組成物。
［１１］
［１］～［１０］のいずれか一つに記載のフェノキシ樹脂組成物であって、
熱伝導性樹脂組成物に用いる、フェノキシ樹脂組成物。
［１２］
［１］～［１１］のいずれか一つに記載のフェノキシ樹脂組成物を含む、樹脂材料。 Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various configurations other than those described above can be adopted. Furthermore, the present invention is not limited to the above-described embodiments, and modifications and improvements within the scope of the present invention are included in the present invention.
Below, examples of reference forms are given.
[1]
A phenoxy resin having a mesogen structure in its molecule;
A low molecular weight component having a weight average molecular weight Mw of 1,000 or less;
A phenoxy resin composition comprising:
In the molecular weight distribution of the phenoxy resin composition obtained by gel permeation chromatography, the peak area of the low molecular weight component is 7.0% or more and 50.0% or less with respect to 100% of the total peak area.
Phenoxy resin composition.
[2]
The phenoxy resin composition according to [1],
The phenoxy resin composition, wherein the mesogen structure has a structure represented by the following general formula (1):
-A ¹ -x-A ² - (1)
(In the above general formula (1), A ¹ and A ² each independently represent an aromatic group, a condensed aromatic group, an alicyclic group, or an alicyclic heterocyclic group, and x represents a direct bond or a divalent bonding group selected from the group consisting of -O-, -SO2-, -C=C-, -C≡C-, -CO-, -CO-O-, -CO-NH-, -CH=N-, -CH=N-N=CH-, -N=N-, and -N(O)=N-.)
[3]
The phenoxy resin composition according to [1] or [2],
The phenoxy resin having a mesogen structure in the molecule is
The composition has a structural unit derived from a polyfunctional phenol compound having two or more hydroxy groups in the molecule, and a structural unit derived from a polyfunctional epoxy compound having two or more epoxy groups in the molecule,
A phenoxy resin composition, wherein at least one of the polyfunctional phenol compound and the polyfunctional epoxy compound has the mesogen structure in the molecule.
[4]
The phenoxy resin composition according to [3],
A phenoxy resin composition, wherein the phenoxy resin having a mesogen structure in the molecule is obtained by reacting a polyfunctional phenol compound represented by the following general formula (A) with a polyfunctional epoxy compound represented by the following general formula (B):

(In general formula (A), R1 ^and R3 ^each independently represent a hydroxy group, R2 ^and R4 ^each independently represent one selected from a hydrogen atom, a linear or cyclic alkyl group having 1 to 6 carbon atoms, a phenyl group, and a halogen atom, a and c each independently represent an integer from 1 to 3, and b and d each independently represent an integer from 0 to 2, provided that a+b and c+d each independently represent an integer from 1 to 3. R represents a mesogen structure represented by general formula (1) above, n is 0 or 1, and when n is 0, a condensed ring may be formed by two benzene rings.)

(In general formula (B), R5 ^and R7 ^each independently represent a glycidyl ether group, R6 ^and R8 ^each independently represent one selected from a hydrogen atom, a linear or cyclic alkyl group having 1 to 6 carbon atoms, a phenyl group, and a halogen atom, e and g each independently represent an integer from 1 to 3, and f and h each independently represent an integer from 0 to 2, provided that e+f and g+h each independently represent an integer from 1 to 3. R represents a mesogen structure represented by general formula (1) above, n is 0 or 1, and when n is 0, a condensed ring may be formed by two benzene rings.)
[5]
The phenoxy resin composition according to [4],
A phenoxy resin composition, wherein the phenoxy resin having a mesogenic structure in the molecule contains a repeating unit represented by the following general formula (b):

(In the general formula (b), b, d, R, n, R2 ^and R4 ^are defined as in the general formula (A), and f, h, R6 ^and R8 ^are defined as in the general formula (B). * represents a bond.)
[6]
The phenoxy resin composition according to [4],
A phenoxy resin composition, wherein the phenoxy resin having a mesogenic structure in the molecule contains a repeating unit represented by the following general formula (c):

(In formula (c), b, d, R, n, R2 ^and R4 ^are defined as in formula (A), and f, h, R6 ^and R8 ^are defined as in formula (B). * represents a bond.)
[7]
The phenoxy resin composition according to any one of [3] to [6],
The phenoxy resin is obtained by reacting the polyfunctional phenol compound with the polyfunctional epoxy compound,
The phenoxy resin composition, wherein the low molecular weight component includes unreacted monomer and a low molecular weight product of the unreacted monomer.
[8]
The phenoxy resin composition according to any one of [3] to [7],
In the molecular weight distribution of the phenoxy resin composition, the peak area of the low molecular weight component not containing a monomer component is 2.0% or more and 25.0% or less relative to the total peak area (100%).
Phenoxy resin composition.
[9]
The phenoxy resin composition according to any one of [1] to [8],
A phenoxy resin composition, wherein the Mw of a high molecular weight component having a Mw of more than 1,000 is more than 1,000 and not more than 200,000.
[10]
The phenoxy resin composition according to any one of [1] to [9],
A phenoxy resin composition, wherein the molecular weight distribution (Mw/Mn) of a high molecular weight component having Mw exceeding 1,000 is 1.00 or more and 5.00 or less.
[11]
The phenoxy resin composition according to any one of [1] to [10],
A phenoxy resin composition for use in a thermally conductive resin composition.
[12]
A resin material comprising the phenoxy resin composition according to any one of [1] to [11].

The present invention will be described in detail below with reference to examples, but the present invention is not limited to the description of these examples.

The raw materials shown in Table 1 are as follows:
(Epoxy Compound)

YX4000: Tetramethylbiphenyl type epoxy resin represented by the following chemical formula (bifunctional epoxy compound, having a mesogen structure, manufactured by Mitsubishi Chemical Corporation, YX4000)

16DON: 1,6-dihydroxynaphthalene type epoxy resin (difunctional epoxy compound, has a mesogen structure, manufactured by DIC Corporation, HP-4032D)

YL6121: a 1:1 mixture of the epoxy resins shown below (bifunctional epoxy compound, having a mesogen structure, manufactured by Mitsubishi Chemical Corporation, YL6121)

(Phenol compounds)
HQHBA: ester group-containing bisphenol (HQHBA, bifunctional phenolic compound, with mesogen structure, manufactured by Ueno Pharmaceutical Co., Ltd.)

26DON: 2,6-dihydroxynaphthalene (bifunctional phenol compound, has a mesogenic structure, manufactured by Tokyo Chemical Industry Co., Ltd.)

BP: 4,4'-dihydroxybiphenyl (bifunctional phenol compound, has a mesogen structure, manufactured by Tokyo Chemical Industry Co., Ltd.)

Resveratrol: Resveratrol (trifunctional phenolic compound, has a mesogen structure, manufactured by Evolva)

<Synthesis of phenoxy resin (preparation of phenoxy resin composition)>
(Examples 1 to 14)
According to the types and amounts (parts by weight) shown in Table 1, an epoxy compound, a phenol compound, triphenylphosphine (TPP), and a solvent (methyl ethyl ketone) were added to a reactor, and reacted while removing the solvent according to the reaction temperature and reaction time shown in Table 1. The reaction was stopped after it was confirmed by GPC that a phenoxy resin having the desired molecular weight was obtained and that the amount of low molecular weight components having a weight average molecular weight Mw of 1,000 or less was a predetermined amount. In addition, the amount of the low molecular weight components was reduced by appropriate purification.
As a result of the above, a resin composition was obtained that contains a phenoxy resin containing a repeating unit represented by the following chemical formula and a predetermined amount of a low molecular weight component having a weight average molecular weight Mw of 1,000 or less.

- Phenoxy resin (YX4000/26DON)

- Phenoxy resin (16DON/HQHBA)

- Phenoxy resin (YX4000/HQHBA)

- Phenoxy resin (YX4000/BP)

- Phenoxy resin (YX4000/HQHBA/Resveratrol)

- Phenoxy resin (YL6121/HQHBA)

In the formula, R is a hydrogen atom or a methyl group, and the four Rs bonded to each biphenyl group are the same. The phenoxy resin is a mixture containing 50% R=H and 50% R= _CH3 .

(Comparative Example 1)
As the phenoxy resin, linear phenoxy resin 1: bisphenol A type phenoxy resin (no mesogen structure, manufactured by Mitsubishi Chemical Corporation, YP-55) represented by the following chemical formula was used.

(Comparative Examples 2, 4, and 5)
A phenoxy resin was obtained in the same manner as in Example 1, except that the epoxy compound, phenol compound, weight ratio, reaction temperature, and reaction time shown in Table 1 were used.

(Comparative Example 3)
The phenoxy resin obtained in Example 9 was dissolved in a good solvent to adjust the solid concentration to about 40%, and then reprecipitation was carried out using 8 times the amount of methanol to obtain a phenoxy resin with a reduced monomer content.

(Molecular weight, dispersity, and peak area)
The measurement conditions for GPC are as follows.
- Gel permeation chromatography device HLC-8320GPC manufactured by Tosoh Corporation
Column: TSK-GEL GMH, G2000H, Super HM-M manufactured by Tosoh Corporation
Detector: RI detector for liquid chromatography Measurement temperature: 40°C
Solvent: THF
Sample concentration: 2.0 mg/milliliter

The weight average molecular weight (Mw), number average molecular weight (Mn), and polydispersity index (PDI: Mw/Mn) were calculated using polystyrene equivalent values obtained from the calibration curve of standard polystyrene (PS) obtained by GPC measurement.

Based on the molecular weight data obtained by the GPC measurement, the peaks in the molecular weight distribution were classified into high molecular weight components (A) with Mw of more than 1k, low molecular weight components (B) with Mw of 1k or less that do not contain monomers, and monomers (C). The sum of (B) and (C) is the low molecular weight component with Mw of 1k or less.

When the total area of the molecular weight distribution obtained by the above GPC measurement was taken as 100%, the area ratio (%) of the peak area corresponding to the low molecular weight components (above (B) + (C)) with Mw of 1k or less contained in the phenoxy resin to be measured was calculated.

The obtained phenoxy resin composition was evaluated based on the following evaluation items.

(Liquidity)
Using a cone plate viscometer CV-1S manufactured by Toa Kogyo Co., Ltd., about 0.1 g of the pulverized phenoxy resin was weighed out and placed on a stage preheated to a predetermined temperature (150°C, 165°C, 180°C), and the torque value was measured when the cone rotation speed was 94 rpm to 750 rpm. The measured torque value was used to calculate the melt viscosity (mPa s) of the phenoxy resin.
The melt viscosity of the phenoxy resin composition was evaluated based on the following evaluation criteria.
In Table 1, melt viscosity at 180° C. exceeding 10 mPa·s was evaluated as ×, melt viscosity at 180° C. not more than 10 mPa·s but more than 5 mPa·s was evaluated as △, and melt viscosity at 180° C. not more than 5 mPa·s was evaluated as ○. The detection limit indicates that the melt viscosity was too low to measure.

(Thermal Conductivity)
The thermal diffusivity and thermal conductivity of the obtained phenoxy resin composition were measured according to the following procedures.
- Preparation of resin molded product 100 parts by weight of the obtained phenoxy resin composition was mixed with 2 parts by weight of a catalyst (2-methylimidazole), and the mixture was set in a mold coated with a release agent, and compression molding was performed at 180°C for 30 minutes to obtain a resin molded product with a diameter of 10 mm and a thickness of 1 mm. Then, curing was performed in an oven at 180°C for 180 minutes to obtain a resin molded product (thermal conductivity measurement sample 1).
Density of resin molded body Density measurement was performed in accordance with JIS K 6911 (general test method for thermosetting plastics). Test pieces were cut from the above resin molded body to a length of 2 cm, width of 2 cm, and thickness of 2 mm. The unit of density (ρ) is g/cm3.

Specific Heat of Resin Molded Article The specific heat (Cp) of the above-obtained resin molded article was measured by a DSC method.

Measurement of thermal conductivity of resin molded body From the obtained resin molded body, a test piece was processed to a diameter of 10 mm and a thickness of 1 mm for thickness direction measurement. Next, the thermal diffusion coefficient (α) in the thickness direction of the plate-shaped test piece was measured by the laser flash method using a Xe flash analyzer TD-1RTV manufactured by ULVAC. The measurement was performed under the condition of air atmosphere and 25°C.
For the resin molded body, the thermal conductivity was calculated based on the measured values of the thermal diffusion coefficient (α), specific heat (Cp), and density (ρ) obtained, according to the following formula.
Thermal conductivity [W/m・K] = α [m ² /s] × Cp [J/kg・K] × ρ [g/cm ³ ]
In Table 1, the thermal conductivity of the resin molded body is indicated as "resin thermal conductivity."

The thermal conductivity of the resulting resin was evaluated based on the following criteria.
In Table 1, the resin thermal conductivity was indicated as × when it was 0.26 W/m·K or less, as △ when it was greater than 0.26 W/m·K and less than 0.29 W/m·K, and as ○ when it was 0.29 W/m·K or more.

The phenoxy resin compositions of Examples 1 to 11 showed superior fluidity compared to Comparative Examples 2 and 3, and superior thermal conductivity compared to Comparative Examples 1, 4, and 5. Such phenoxy resin compositions can be used as resin materials, and can be suitably used as heat dissipating insulating materials such as heat dissipating insulating substrates and sheets.

100 Metal base substrate 101 Metal substrate 102 Insulating layer 103 Metal layer

Claims (12)

A phenoxy resin having a mesogen structure in its molecule;
A low molecular weight component having a weight average molecular weight Mw of 1,000 or less;
A phenoxy resin composition comprising:
In the molecular weight distribution of the phenoxy resin composition obtained by gel permeation chromatography, the peak area of the low molecular weight component is 7.0% or more and 50.0% or less with respect to 100% of the total peak area;
The phenoxy resin composition, wherein the low molecular weight component is an unreacted monomer component contained in the phenoxy resin and a polymer of the monomer component. The phenoxy resin composition according to claim 1,
The phenoxy resin composition, wherein the mesogen structure has a structure represented by the following general formula (1):
-A ¹ -x-A ² - (1)
(In the above general formula (1), A ¹ and A ² each independently represent an aromatic group, a condensed aromatic group, an alicyclic group, or an alicyclic heterocyclic group, and x represents a direct bond or a divalent bonding group selected from the group consisting of -O-, -SO ₂ -, -C=C-, -C≡C-, -CO-, -CO-O-, -CO-NH-, -CH=N-, -CH=N-N=CH-, -N=N-, and -N(O)=N-.) The phenoxy resin composition according to claim 1 or 2,
The phenoxy resin having a mesogen structure in the molecule is
The composition has a structural unit derived from a polyfunctional phenol compound having two or more hydroxy groups in the molecule, and a structural unit derived from a polyfunctional epoxy compound having two or more epoxy groups in the molecule,
A phenoxy resin composition, wherein at least one of the polyfunctional phenol compound and the polyfunctional epoxy compound has the mesogen structure in the molecule. The phenoxy resin composition according to claim 3,
The phenoxy resin having a mesogen structure in the molecule is obtained by reacting a polyfunctional phenol compound represented by the following general formula (A) with a polyfunctional epoxy compound represented by the following general formula (B) :
The phenoxy resin composition , wherein the mesogen structure has a structure represented by the following general formula (1) :

(In general formula (A), ^R1 and ^R3 each independently represent a hydroxy group, ^R2 and ^R4 each independently represent one selected from a chain or cyclic alkyl group having 1 to 6 carbon atoms, a phenyl group, and a halogen atom, a and c each independently represent an integer from 1 to 3, and b and d each independently represent an integer from 0 to 2, provided that a+b and c+d each independently represent an integer from 1 to 3. R represents a mesogen structure represented by general formula (1) above, n is 0 or 1, and when n is 0, a condensed ring may be formed by two benzene rings.)

(In general formula (B), ^R5 and ^R7 each independently represent a glycidyl ether group, ^R6 and ^R8 each independently represent one selected from a linear or cyclic alkyl group having 1 to 6 carbon atoms, a phenyl group, and a halogen atom, e and g each independently represent an integer from 1 to 3, and f and h each independently represent an integer from 0 to 2, provided that e+f and g+h each independently represent an integer from 1 to 3. R represents a mesogen structure represented by general formula (1) above, n is 0 or 1, and when n is 0, a condensed ring may be formed by two benzene rings.)
-A ¹ -x-A ² - (1)
(In the above general formula (1), A ¹ and A ² each independently represent an aromatic group, a condensed aromatic group, an alicyclic group, or an alicyclic heterocyclic group, and x represents a direct bond or a divalent bonding group selected from the group consisting of -O-, -SO ₂ -, -C=C-, -C≡C-, -CO-, -CO-O-, -CO-NH-, -CH=N-, -CH=N-N=CH-, -N=N-, and -N(O)=N-.) The phenoxy resin composition according to claim 4,
A phenoxy resin composition, wherein the phenoxy resin having a mesogenic structure in the molecule contains a repeating unit represented by the following general formula (b):

(In the general formula (b), b, d, R, n, ^R2 and ^R4 are defined as in the general formula (A), and f, h, ^R6 and ^R8 are defined as in the general formula (B). * represents a bond.) The phenoxy resin composition according to claim 4,
A phenoxy resin composition, wherein the phenoxy resin having a mesogenic structure in the molecule contains a repeating unit represented by the following general formula (c):

(In formula (c), b, d, R, n, ^R2 and ^R4 are defined as in formula (A), and f, h, ^R6 and ^R8 are defined as in formula (B). * represents a bond.) The phenoxy resin composition according to any one of claims 3 to 6,
The phenoxy resin is a phenoxy resin composition obtained by reacting the polyfunctional phenol compound with the polyfunctional epoxy compound. The phenoxy resin composition according to any one of claims 3 to 7,
A phenoxy resin composition, wherein in the molecular weight distribution of the phenoxy resin composition, the peak area of the low molecular weight component not containing a monomer component is 2.0% or more and 25.0% or less relative to 100% of the total peak area. The phenoxy resin composition according to any one of claims 1 to 8,
A phenoxy resin composition, wherein the Mw of a high molecular weight component having a Mw of more than 1,000 is more than 1,000 and not more than 200,000. The phenoxy resin composition according to any one of claims 1 to 9,
A phenoxy resin composition, wherein the molecular weight distribution (Mw/Mn) of a high molecular weight component having Mw exceeding 1,000 is 1.00 or more and 5.00 or less. The phenoxy resin composition according to any one of claims 1 to 10,
A phenoxy resin composition for use in a thermally conductive resin composition. A resin material comprising the phenoxy resin composition according to any one of claims 1 to 11.

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